Tie-rodless double acting press

ABSTRACT

A NOVEL TOGGLE PRESS WHEREIN THE GROSS VERTICAL MOVEMENTS OF TWO MOVABLE PLATENS IS ACHIEVED WITH A SINGLE ACTUATING RAM BY USE OF TOGGLE ASSEMBLIES AND WITH EACH PLATEN ACTING AS A COUNTERWEIGHT TO AID IN RAISING THE OTHER PLATEN. THIS PRESS UTILIZES AUXILIARY POWER MEANS INDEPENDENT OF THE SINGLE ACTUATING RAM, TO APPLY MOLD   ING PRESSURE, AND ONE EMBODIMENT OF THE INVENTION THIS AUXILIARY POWER MEANS IS MOUNTED ON EACH TOGGLE ASSEMBLY AND ACTS ON A PIVOT PIN ATTACHED TO THE UPPER PLATEN ASSEMBLY.

Oct. 12, 1971 (3|DGE HAL 3,611,497

TIE-ROBLESS DOUBLE ACTING PRESS Filed May 1, 1969 3 Sheets-Sheet 1INVENTUR.

Lester Gidge BY PM ""Paam-n A T TORNEYS Vulmor R. Poulin Jr.

a Sheets-Sheet 2 L. GIDGE ETAL TIE-RODLESS DOUBLE ACTING PRESS Oct. 12,1971 Filed llay i, 1969 BY Volmor R. Poulin Jr. Flu/Am PM ATTORNEYS 12,1971 L. GIDGE ETAL 3,611,497

TIE-RODLESS DOUBLE ACTING PRESS Filedua 1, 1969 3 Sheets-Sheet sINVENTOR. Le Gidge B V0 0 R. Poulin Jr.

ATTORNEYS United States Patent O 3,611,497 TIE-RODLESS DOUBLE ACTINGPRESS Lester Gidge and Valmor R. Poulin, Jr., Nashua, N.H., assignors toNashua Industrial Machine Corporation, Nashua, NH.

Filed May 1, 1969, Ser. No. 820,894 Int. Cl. 153% 1/16 US. Cl. 18.-16 T8 Claims ABSTRACT OF THE DISCLOSURE A novel toggle press wherein thegross vertical movements of two movable platens is achieved with asingle actuating ram by use of toggle assemblies and with each platenacting as a counterweight to aid in raising the other platen. This pressutilizes auxiliary power means, independent of the single actuating ram,to apply molding pressure, and one embodiment of the invention thisauxiliary power means is mounted on each toggle assembly and acts on apivot pin attached to the upper platen assembly.

BACKGROUND OF THE INVENTION A considerable amount of effort has beenexpended over the years in providing improved compression moldingapparatus. For example, such apparatus is described in US. Pat.2,792,592 to R. G. McGee; US. Pat. 3,205,551 to R. Neubauer et al., andmany others. Most such patents comprise tie-rods through the platensthereof to provide guidance for the platens on the opening and closingof the press. One said inventor, W. G. Corson, in apparatus described inUS. Pat. 2,624,915, avoided the use of such tie-rods, but his was aspecial purpose press comprising only one moving platen assembly.

In general, all previous inventors have attempted to improve themechanical advantage offered by such presses, or to improve the strokelength or compression rate for some special purpose. Nevertheless, allprior art presses have some drawbacks, and it has been a particularproblem to provide a relatively inexpensive press in which a highmechanical advantage is achieved, and on which conventional tie-rods areavoided to maximize access to the work area. It has also been a problemto provide a press which can be opened and closed quickly and which hasa platen-travel speed which is not limited throughout its travel by thelimitations of the velocity of a conventional power stroke mechanism.

SUMMARY OF THE INVENTION It is an object of the instant invention toprovide a novel toggle press with a highly efficient leverage system.

Another object of the invention is to provide a toggle press which doesnot require conventional tie-rods for guidance of the platens during theOpening and closing of the press, but on which press the levers of thetoggle system provide a substantial part of the guidance for the platenassemblies.

Still another object of the invention is to provide a toggle presshaving excellent acceleration and deceleration characteristics on theopening and closing of the press.

A further object of the invention is to provide a Patented Oct. 12, 1971ice toggle press whereby the mass of the bottom platen assembly thereofis utilized in lifting the mass of the top platen assembly thereofduring the opening of the press, and where the mass of the top platenassembly is utilized in lifting the mass of the lower platen assemblyduring the closing of the press.

Another object of the invention is to provide a press wherein thevelocity at which the platens are moved apart is substantially greaterthan is usual in such apparatus.

Other objects of the invention will be obvious to those skilled in theart on reading the instant application.

These objects have been substantially achieved by the construction of anovel toggle press comprising four multiple lever-type toggle assemblieswhich connect an upper platen carrier assembly and a lower platencarrier assembly. These connections are substantially at the corners ofthe platen assemblies and allow the toggle assemblies to serveeffectively to guide the platens in their gross vertical movements, i.e.the movements which bring the platens back and forth between the openposition and that position at which the compression or molding, strokemust begin. Each toggle system comprises a double-acting master leverattached to a fixed pivot on the fixed framework of the press apparatus.One end of this master lever is pivotally attached to the upper platenassembly. The other end of the master lever is pivotally attached to twoadditional levers, the first of which is pivotally attached at itsopposite end to the press-actuating ram and the second of which ispivotally attached at its opposite end to the lower platen assembly.This lever arrangement provides a force-transfer means whereby potentialenergy being recovered from whichever platen assembly is being loweredis partly utilized to aid in raising whichever platen is being raised.

ILLUSTRATIVE EMBODIMENT OF THE INVENTION In the drawings:

FIG. 1 is a front elevational view of the novel toggle press of theinvention, in closed position;

FIG. 2 is a side elevational view of the toggle press, in closedposition;

FIG. 3 is a view similar to FIG. 1, showing the press in open position;

FIG. 4 is a schematic diagram of the toggle-type mechanism used with theapparatus of the invention showing said mechanism in both open and shutpositions and providing some specific detail with respect to anglesjoining the various lever arms;

FIG. 5 is a partial perspective view of the apparatus shown in FIGS. 1and 2 but showing placement of the power-stroke cylinders thereon;

FIGS. 6 and 7 are schematic diagrams illustrating the mode of operationof the power-stroke cylinders.

Referring first to FIGS. 1, 2 and 3, it is seen that toggle pressapparatus 12 is mounted on crossbar 14 and support plate 15 of framestructure 16. Also mounted on crossbars 14 is a hydraulic power cylinder18 for actuating ram 20. Support arms 22 and 23 are mounted on supportplate 15 and each said arm comprises a fixed pivot pin 24 providingmeans for positioning two toggle assemblies 26, one on each side of eachfixed pivot pin 24.

Each of the four toggle lever assemblies 26 comprises a toggle lever 28attached by fixed pivot pin 24 to fixed support arms 22 or 23. Pivotallyattached to each toggle lever 28 at the outwardly extremity thereof isan upper platen lever arm 30; pivotally attached to the inner extremityof toggle levers 28, and to each other, are ram lever 32 and lowerplaten lever 34. Ram lever 32 is pivotally attached to a head 36 fixedon ram thereby forming means whereby vertical movement of ram 20 candetermine the position of each of levers 32, 34, 28 and 30.

It will be seen that toggle lever assembly, or mechanical linkage means26 is thus achieved in which the balance lever 28, centrally pivoted at24, causes the weight of the upper platen 52 (through link, or lever, tosubstantially counterbalance the weight of the lower platen 44 (throughlink, or lever, 34) and causes the platens to move toward and away fromeach other along substantially co-extensive vertical paths.

The power actuated ram mechanism 35, is operably connected by togglelever 32 and head 36 to the linkage means 26 at pivot 40, which is across pin, or rod, of round cross section as are the other pivot pins ofthe press.

The pivotal connections between head 36 and ram lever 32 is achieved bymeans of a pivot pin 38 which serves two sets of toggle assemblies 26 asshown in FIGS. 1 and 2 and one directly behind each of them but notvisible in the drawing. Similarly another pivot pin 40 forms means topivotally connect levers 28, 32 and 34. Pivot pin 40 also serves twosets of toggle assemblies 26. Still other pivot pins 42 and 41 form thepivotal connection by which lever 28 is pivotally connected to lowerplaten carrier assembly 44, and on which lever 30 is pivotally connectedto upper platen carrier assembly 52, respectively.

Mounted on each side of lower platen carrier assembly 44 is apositioning member 46. Similarly a positioning member is mounted on eachside of upper platen carrier assembly 52. Guide pins 54 are common toand protrude through each pair of members 50 and 46.

Referring to FIGS. 5, 6 and 7, it is seen that pivot pin 43 is mountedin a vertically-elongated hole 56 which has been cut into lever arms 30.A piston rod 58 forms means for applying pressure to the top of pin 43.

Piston rod 58 is actuated by auxiliary, power-actuated ram mechanismincluding a so-called pancake cylinder 60, which itself is actuated by ahydraulic power means 62. There is one such cylinder 60 at each end ofeach pivot pin 43, i.e. at each of the four upper corners of theapparatus being described. These pancake cylinders 60 comprisecompression means whereby the power stroke required for moldingoperations can be accomplished independently of the gross positioningstroke whereby the platens are brought together just short of the pointthat the power stroke must start.

Referring to FIG. 6, it is seen that piston rod 58 is curved to fitpivot pin 43 and that the pivot pin is positioned toward the top ofelongated hole 56 at the time the toggle linkages have place the upperand lower platen assemblies in closed position, i.e. their position justprior to initiation of the power stroke. At this point, pancakecylinders 60 are actuated, and pivot pin 43 is pressed by hydraulicmeans 62, acting through cylinders 60, to the bottom of elongated hole56. This pressure is transmitted through pins 43 to the platen assembly52, thus closing the molds on the pressure stroke. There is nosignificant pressure on the toggle linkage during this pressure strokeactuated by cylinders 60.

When the platens have been closed, pins 43 are in the lower portion ofhole 56 as shown in FIG. 7. Removal of pressure exerted on piston rod 58allows the pins 43 to return to their normal, or no-pressure, positionat the top of hole 56.

Thus the pancake cylinders 60 are only actuated by hydraulic pressureafter the toggle linkages have been used to place the platens in aposition of rest appropriate for starting the power-stroke. Thispressure on cylinders can be released as soon as the power-stroke hasaccomplished its molding mission.

What is claimed is:

1. A toggle-actuated press apparatus of the type described, comprising aframework with a single actuating ram, a vertically-movable upper platenassembly, a vertically-movable lower platen assembly, and a plurality oftoggle assemblies mounted thereon,

each said toggle assembly comprising a plurality of levers forming thesole means for supporting said upper and lower platen assemblies on saidframework, said toggle assembly counter balancing one said platen withthe other and forming means for moderating gross movements of said upperand lower platen assemblies and auxiliary power means, independent ofsaid ram, to provide a relatively short power stroke to at least onesaid platen assembly.

2. An apparatus as defined in claim 1 wherein said auxiliary means toprovide a short power stroke comprises a plurality of short-strokecylinders and a plurality of pistons, each operable by one of saidshort-stroke cylinders forming means to provide a relatively short powerstroke to at least one said platen assembly.

3. An appartaus as defined in claim 2 wherein each said piston ismounted proximate one said toggle assembly and forms means to applyforce to a pivot pin attached to both one said lever and a platenassembly, thereby achieving movement of said platen assembly.

4. An apparatus as defined in claim 2 wherein said shortstroke cylindersare each mounted on the end of a lever which is attached to said upperplaten assembly and said pistons are each mounted within said lever andoperably positioned therein, each to bear against a pivot pin attachedto one of said upper platen assembly and said lever.

5. A toggle-actuated press apparatus of the type described, comprisingan actuating ram, a vertically movable lower platen assembly, avertically movable upper platen assembly, a framework, a plurality oftoggle assemblies mounted thereon, each said toggle assembly comprisinga plurality of levers, counter-balancing one said platen with the other,a first of which levers is pivotally connected for response to verticalmovement of said ram,

a second lever pivotally attached proximate one end thereof to saidfirst lever and to the vertically movable lower platen assembly at theother end thereof,

a third lever pivotally attached to each of said first lever and secondlever at one end thereof and pivotally attached to a fourth lever at theother end thereof.

said fourth lever pivotally attached to the vertically movable upperplaten assembly at an end of said lever remote from the end at whichsaid third lever is pivotally attached thereto,

a fixed pivot point on said third lever between its points of pivotalattachments to (a) said first and second levers, and (b) said fourthlever,

said toggle assemblies being the sole means for supporting said upperand lower assemblies on said framework, and responsive to the movementof said ram to moderate the gross vertical movement of said platenassemblies.

6. Apparatus as defined in claim 5 comprising auxiliary meansindependent of said actuating ram to provide a relatively short powerstroke to at least one said platen assembly.

7. In a press having an upper and lower platen movable toward and awayfrom each other, the combination of:

mechanical linkage means pivotally supporting said platens for suchmovement and counterbalancing the weight of one said platen with theother relative to a fixed pivot axis on said press,

and a single power actuated ram mechanism, operably connected by togglelevers, to said mechanical linkage means to move both of said platenssimultaneously toward and away from each other.

8. A press as specified in claim 7, wherein said upper platen issupported on said mechanical linkage means for limited vertical movementrelative thereto, and

auxiliary power actuated ram mechanism, independent of said first namedram mechanism and mounted on said linkage means, for finally pressingsaid platens come to rest.

' 6 References Cited UNITED STATES PATENTS 2,624,915 1/1953 Corson 18-30LT X 3,278,989 10/1966 Neubauer et al 1816 T 3,340,574 9/1967 OBrien eta1 18l6 T J. HOWARD FLINT, JR., Primary Examiner US. Cl. X.R. 30 LT;25-98

